Organic Broadcaster

Thoughtful planning yields perennial crop of blue fruits

By Jim Riddle and Joyce Ford, Blue Fruit Farm

A high fence prevents deer from devouring the plants at Blue Fruit Farm in Winona, Minn.Photo by Jim Riddle

Blue fruits (blueberries, black currants, elder­berries, aronia, and honeyberries) are quite popular in Europe, and are gaining popularity in the U.S. These berries are great additions to the diversified market farm, and, with thought­ful planning, will produce for many years.

We grow many varieties of blue fruits on our farm near Winona, Minn. We chose these flavorful berries for their health benefits. They are all high in antioxidants, especially aronia berries, which have 4 to 10 times the antioxi­dants of blueberries. Elderberries have anti-viral properties, may help prevent cancer, and are loaded with quercetin, a flavonoid that’s critical for brain health. Black currants have four times the vitamin C of citrus. But the real advantage for us is that they are perennials. After produc­ing annual crops to sell at the Winona Farmers Market in the 80s and 90s, we decided that, if we ever got back into production, we wanted to focus on perennials.

Site Selection and Preparation

When planting perennial fruiting shrubs, it is critical that you choose a site that is well suited to the crops. Preparing the site prior to planting will help provide nutrients and weed control for years to come. These shrubs, if properly managed, will produce for 50 years or more. Time spent on the front end will pay off in the long run.

Choose a site with well-drained soils, preferably with medium to high organic matter content. Choose a sunny location with good air flow. Soil pH should be around 5-5.5 for blueberries. The other fruits tolerate a wider pH range, from 5.5 to 6.8.

When we started prepping our 4-acre field, we refurbished an 8-foot high deer fence. To make sure that fawns could not get through the fence, we added 4-foot high narrow mesh woven wire to the fence perimeter. This has been 100% suc­cessful at excluding deer, which is an absolute necessity in our area.

We spent several days picking rocks. We tilled the field, and picked rocks again. We planted the entire field to oats, wheat, and medium red clover to help build fertility and break weed cycles. We returned the small grain and clover residues to the soil to build organic matter. After a full year of cover crops, we began our 3-year planting schedule. We laid out and tilled one third of our planting beds. We planted cover crops of buckwheat, clover, and sorghum-sudan in the remaining beds to further build fertility and manage weeds. We also sub-soiled all the beds to help break hardpan, allow root penetration, and improve water and nutrient uptake.

Fertility

As I mentioned, blueberries need a lower pH than the other crops we grow. To lower our soil pH using organic methods and approved inputs, we incorporated cover crop residues, and added composted horse manure and peat moss. Then we conducted a soil test, and added a customized micro-nutrient fertilizer blend and elemental sulfur. We mulched with pine straw and ground hardwood bark.

We conduct soil, tissue and pH testing annu­ally. We purchased an easy-to-use soil pH meter for $100. We also do some foliar feeding with fish emulsion and kelp extracts, and now inject these inputs using our irrigation system. We use composted horse manure to top-dress around our plants annually.

Irrigation

While berries need well-drained soil, they also need water, especially when they are getting established and during fruit set and production, as well as periods of drought. We have installed a solar-powered, drip irrigation system to all berry rows and plum trees. We collect rainwater from the roof of a 24’x36’ metal machine shed we built in the field. We have 6,000 gallons of below-ground and above-ground water storage. We ran a 1” PVC line to be able to pump water from our household well, as needed. The irrigation system has 2, 1-gallon-per-hour emitters per plant. We have manual controls, and keep track of which rows get water, for how long.

Birds and the Bees

By far, fruit-eating birds are our most challeng­ing pests. (I used to like robins and bluebirds!) We have tried numerous tactics to deter birds, including scare eye balloons, aluminum pans, fake owls and falcons, scare crows, raptor roosts, and row netting. We installed a Bird Guard sound system, which emits bird stress calls and raptor screams. It is supposed to protect up to 6 acres. It seems to help, but not enough. This year, we plan to install Smart Net overhead netting over about ¾ of the field. All of the bird deterrents are mounted on untreated locust posts, which are allowed in organic production, and we were lucky to source locally.

We are writing pest management action plans for specific insect problems. We use monitoring and hand removal. We initially used Bt for a brief forest tent caterpillar infestation, but prefer not to spray. We use a small propane torch to scorch eastern tent caterpillar nests. We have released beneficial nematodes to help control currant borers and elderberry mites. So far, we have had minimal insect pest damage.

We have had some problems with raccoons— like humans, they love berries! They are not deterred by row netting, so we installed a line of electric fence around the field perimeter. We also live trap and shoot the rascals.

Young berry plants need to be protected from rabbits and mice during the winter. For small plantings, we have used tree wraps, plastic tree guards, chicken wire or hardware cloth. We haven’t had rabbit or mice problems in our field, likely because there are quite a few raptors and our field is quite open.

For weeds, our pre-plant tillage and cover crop­ping was critical in getting them under control in advance. We tried using paper mulch on our first plantings, but it was a failure—frustrating to apply, expensive, and ineffective. We used 20-year landscape fabric covered with hard­wood bark mulch in the beds where we have the best weed control. We have planted white Dutch clover between the beds to help with weed control and to provide food for pollinators. We mow between the beds, alternating so that the clover is allowed to bloom. We do a lot of hand weeding around the plants. We also use a string trimmer and backpack flame weeder, and try to be diligent in preventing weeds from setting seeds.

To manage diseases, we scout the plants frequently, looking for signs of disease. We prune our plants aggressively to maximize air flow and sunlight penetration. When we discover infected plants, we remove them from the field. We have replaced susceptible varieties also, such as Consort black currant, which we discovered was susceptible to powdery mildew. Two years after planting 115 Consort black currants, those plants were pulled from our field and replaced with the variety Titania.

We actively provide food sources and habitat for pollinators and predators. In addition to clover, we have planted native plants, such as New Jersey Tea and butterfly weed, in the field and manage a 4-acre prairie adjacent to the field. This year, we’re adding hairy mountain mint and anise hyssop to the mix. Since we don’t have honeybees, we have installed native bee tube boxes and leave areas for bumblebee nests. We have flowering plants from early to late in the season, and have planted numerous variet­ies of blueberries (16) and honeyberries (9) to increase pollination, and therefore production.

Harvest and Sales

All of our fruits are hand harvested. We have limited cold storage in a large refrigerator, but plan to install a small walk-in cooler. We sell our MOSA-certified organic fruits through a variety of channels. Most of our blueberries are sold directly to people on our customer list, many of whom sign up through our website, www.bluefruitfarm.com. We market some of our fruits to restaurants in Winona and the Twin Cities. We also sell fruit to and through Hoch Orchards, which is located about 12 miles from us.

Jim Riddle and Joyce Ford established Blue Fruit Farm near Winona, Minn. nearly six years ago. They have been involved in all areas of organic, from farming to teaching and helping to write standards. Joyce served on the MOSES board, and Jim was chair of the National Organic Standards Board. Jim currently serves as Organic Research Grants Coordinator for the Ceres Trust.